jQuery Grid Plugin - jqGrid

You have wrong JSON data. Correspond to http://www.json.org/ the strings must be quoted (with " and not with '). You can verify you test JSON data on http://www.jsonlint.com/. An old version of jQuery (1.3.x) and not jqGrid allowed to use incorrect quoting (allowed to use ').

By the way in the first entry there are one more syntax error

['2','product0','300,00 €,'2010-08-18 18:38:36','processed']

you wanted probably

['2','product0','300,00 €','2010-08-18 18:38:36','processed']

(one ' after €). The correct data should looks like following

{"page": 1,"total": 1,"rows": [
    {"id": "2", "cell": ["2","product0","300,00 €","2010-08-18 18: 38: 36","processed"]},
    {"id": "23″,"cell": ["000023","Product1","100,00 €","2010-09-07 15: 16: 14","processed"]},
    {"id": "19″,"cell": ["19","Product2","400,00 €","2010-09-01 18: 08: 12","processed"]}
 ]}

So you use just replace your server code to produce " instead of '. I don't recommend in general use manual encoding of JSON strings. There are good JSON serializer depend on the language and technology which you use on the server. For example if the string which you want to serialize has already " symbol it must be escaped (replaced to "). in  http://www.json.org/ described much more such examples.

Best regards
Oleg